1. Field of the Invention
This invention relates to a metal-work tool, and particularly to a pneumatic metal-work tool for punching hole and edging a metal sheet.
2. Description of the Prior Art
A conventional pneumatic metal-work tool comprises a casing mounted with a piston and a piston rod; one end of the piston rod extends into a hydraulic chamber on the front end of the casing; the hydraulic chamber is mounted with a push rod extended out of the same; one end of the push rod is connected with a punch assembly; as soon as the pressure air enters the casing, the pressure air will drive the piston to move; then, the piston rod in the hydraulic chamber will be pushed in to provide a pressure, which causes the push rod to move and to drive a punch assembly to punch a hole in a metal sheet; the hydraulic chamber in the front end of the casing is used for converting a pneumatic force into a hydraulic force, which can provide a steady and high punching force; however, after the tool is used for a long time, a leakage might take place between the hydraulic chamber and the cylinder; in that case, the punching force of the hydraulic pushing force converted from the pressure air might be reduced; consequently, a calibration to the pressure must be done after the oil being replenished to the hydraulic chamber.
The prime object of the present invention is to provide a pneumatic metal-work tool, in which the outer surface of the push rod is mounted with a spring, of which one end is pushed against a threaded base, while other end thereof is pushed against a ring-shaped plate to provide the push rod with a return force. The hydraulic chamber is filled with oil, and one end of the piston rod extends into the hydraulic chamber; as long as the hydraulic chamber is filled with oil over one half of its volume, the hydraulic chamber will have no residual air. When the piston rod is driven with the pressure air, the hydraulic chamber will convert that force into a steady punch force to enable the punch assembly to work.
Another object of the present invention is to provide a pneumatic metal-work tool, in which one end of the round rod of the push rod extends into a cylindrical hole of a threaded base, while the other end thereof has a ring-shaped plate with a larger diameter; a round rod on the other end of the ring-shaped plate is mounted with an o-ring and a ring seal; the cylindrical hole for mounting the push rod is partitioned into two spaces, of which one space is mounted with a spring, and one end of the spring is pushed against the ring-shaped plate so as to provide the push rod with a return force; the other space thereof is in communication with the hydraulic chamber of the push rod; the two spaces are separated by means of the o-ring so as to prevent from oil leakage. When the piston rod is pushed towards the hydraulic chamber of the push rod, the oil in the hydraulic chamber will be expanded in one direction as a result of pressure so as to provide the push rod with a punching force.
Still another object of the present invention is to provide a pneumatic metal-work tool, in which the push rod of the metal-work tool is mounted with a connection pipe; one end of the push rod has a threaded portion to be engaged together with a threaded base; the center of the threaded base has a cylindrical hole mounted with an oil seal, a buffer washer and a piston rod; the buffer washer is to provide a shock-proof function upon the push rod returning, and to prevent oil from infiltrating into the center chamber of the casing.
A further object of the present invention is to provide a pneumatic metal-work tool, in which the push rod is mounted with a connection pipe, and one end thereof is mounted with a threaded base, of which the outer end of a ring-shaped plate is in contact with the end thereof, while the outer end thereof is mounted with a threaded sleeve; the center of threaded base has a threaded hole to be mounted with a threaded portion of the punch assembly; different diameters of punch holes of the punch assembly can be replaced by means of disassembling the threaded portion.
A still further object of the present invention is to provide a pneumatic metal-work tool, in which one end of the C-shaped base in the punch assembly has a threaded cylinder, which is screwed in a threaded base of the hydraulic push-rod assembly; the center of the threaded cylinder has a cylindrical hole for receiving a punch shaft of a guide shaft; one end of the punch shaft has a round shaft will a smaller diameter, and one end of the round shaft is inserted into a cylindrical hole of the guide sleeve; the punch shaft is mounted with a spiral spring, which can provide the punch shaft with a returning force after each punching.
Yet another object of the present invention is to provide a pneumatic metal-work tool, in which the threaded cylinder of the C-shaped base in the punch assembly is mounted in a threaded hole of a threaded base of the hydraulic push-rod assembly; the threaded portion of the threaded cylinder is mounted with a threaded positioning ring; the spring of the C-shaped base is fixed in place with the threaded positioning ring after the direction being adjusted as desired so as to have he punch assembly fastened in place.
Yet still another object of the present invention is to provide a pneumatic metal-work tool, in which one side of the C-shaped base of the punch assembly has an opening; both sides of the opening are mounted with a guide sleeve and a punch base respectively; the guide sleeve is mounted to one end of the punch shaft; the center of the punch base has a punch hole, which is used for punching a hole in a metal sheet upon the metal-work tool being operated.
Yet a further object of the present invention is to provide a pneumatic metal-work tool, in which one side of the C-shaped base of the metal-work tool is mounted with a guide sleeve and a punch base by means of threaded portion of a threaded base; the C-shaped base can be removed if necessary so as to replace a punch shaft, a guide sleeve and a punch base having different diameter.
Yet still a further object of the present invention is to provide a pneumatic metal-work tool, in which the threaded base on the front end of the metal-work tool is mounted with a punch assembly by means of threads; both sides of the opening of the C-shaped base are mounted with punch assemblies so as to punch a hole in a metal sheet.
Yet still a further object of the present invention is to provide a pneumatic metal-work tool, in which the front end of the metal-work tool has a threaded base to be mounted with a punch assembly; both sides of the C-shaped base are furnished with edging assemblies so as to edge one end of a metal sheet.